Hormonal Communication Flashcards
Hormone
Molecule released by endocrine glands directly into the blood to act as chemical messengers to carry a signal to target cells
Endocrine Gland
Glands that secrete hormones directly into the blood due to the capillaries running through them
Exocrine Gland
Gland that secretes enzymes into a duct that leads to the duodenum in the pancreas
Target Cell
Cells that have specific receptors in their membrane that the hormones are complementary in shape to.
Types of hormone
Steroid based, non-steroid based
How are steroid based hormones detected?
Hormone passes through phospholipid bilayer of cell, bind to receptors in the cytoplasm or nucleus to form a hormone-receptor complex, complex acts as a transcription factor that can facilitate or inhibit the transcription of a gene
How are non-steroid based hormones detected?
Original hormone acts as a first messenger, binds to receptor in the plasma membrane, activates secondary messenger, secondary messenger can trigger events in the cell
Example of secondary messenger
cAMP
Why are steroid based hormones detected in the way they are?
They are lipid soluble
Why are non-steroid based hormones detected in the way they are?
They are hydrophilic so can’t get through the phospholipid bilayer
Examples of endocrine glands
Thyroid, pituitary, adrenal, testis, pineal, thymus, pancreas, ovary
Name and function of hormone secreted by thyroid gland
Thyroxine, controls rate of metabolism and rate that glucose is used up in respiration
Name and function of a hormone secreted by pituitary gland
ADH, increases reabsorption of water in the kidneys
Name and function of hormone secreted by adrenal gland
Adrenaline, increases heart and breathing rate for the fight and flight response
Name and function of hormone secreted by testis
Testosterone, controls sperm production
Name and function of hormone secreted by pineal gland
Melatonin, control of daily cycle
Name and function of hormone secreted by thymus gland
Thymosin, promotes production and maturation of white blood cells
Name and function of hormone secreted by pancreas
Insulin, converts excess glucose into glycogen in the liver
Name and function of hormone secreted by ovary
Oestrogen, controls ovulation
Structure of adrenal gland
Made of adrenal cortex and medulla, cortex is the outer region, medulla is the inner region
Hormones produced by the adrenal cortex
Glucocorticoids, mineralocorticoids, androgens
Examples of glucocorticoids with their functions
Cortisol to regulate metabolism and regulate blood pressure, corticosterone to regulate immune response and suppress inflammatory reactions
Examples of mineralocorticoids with their functions
Aldosterone to control blood pressure by maintaining the pressure between salt and water
What controls the release of hormones from the adrenal cortex?
Hypothalamus, hormones released from the pituitary gland
What controls the release of hormones from the adrenal medulla?
Stimulation of the sympathetic nervous system
Hormones secreted by the adrenal medulla
Adrenaline, noradrenaline
Role of noradrenaline
Works with adrenaline to increase heart rate, widen pupils and air passages in the lungs and narrow blood vessels in non-essential organs
Type of glandular tissue in the pancreas
Endocrine, exocrine
What does the exocrine tissue in the pancreas make?
Amylases, proteases, lipases, pancreatic juice
How does the exocrine tissue in the pancreas function?
Products secreted into a duct that leads to the pancreatic duct which goes to the duodenum
What does the endocrine tissue in the pancreas make?
Insulin, glucagon
Where is the endocrine tissue in the pancreas?
Islets of Langerhans
What do Islets of Langerhans look like under a microscope?
Large spherical clusters, stained light pink
Different types of cells in the Islets of Langerhans
Alpha, beta
What do acinar cells look like?
Berry-like clusters
What do alpha cells make?
Glucagon
What do beta cells make?
Insulin
How to differentiate between alpha and beta cells?
Differential stain, beta cells are stained blue, alpha cells are stained pink
Glycogenolysis
When glycogen is broken down in liver and muscle cells to release glucose into the bloodstream
Gluconeogenesis
Production of glucose from non-carbohydrate sources
Glycogenesis
The production of glycogen
How does insulin regulate blood glucose concentration?
Increase detected by beta cells in Islets of Langerhans, insulin secreted into the bloodstream, binds to glycoprotein receptors, increases the rate of absorption of glucose by cells, increases the respiratory rate, glycogenesis, increases rate of glucose to fat conversion, inhibits glucagon release, decreases blood glucose concentration
How does insulin increase the rate of absorption of glucose by cells?
Binding to the receptor changes the tertiary structure of the glucose transport protein channels, allows more glucose to enter the cell
How does insulin increase the respiratory rate?
Activates enzymes
Where does negative feedback come in with insulin?
Decrease in blood glucose concentration detected by beta cells, insulin secretion reduced
How does glucagon regulate blood glucose concentration?
Decrease in blood glucose concentration detected by alpha cells in the islets of Langerhans, secrete glucagon, glucagon binds to receptors on liver and fat cells, increases glycogenolysis and gluconeogenesis, reduces the amount of glucose absorbed by the liver cells
What kind of hormone are insulin and glucagon?
Antagonistic
Process of the control of insulin secretion
Blood glucose concentration rises, glucose enters beta cell by a glucose transporter, glucose metabolised in respiration to produce ATP, ATP binds to potassium channels, ATP-sensitive potassium channels close, membrane depolarises, voltage-gated calcium channels open, calcium ions enter the cell and cause the secretory vesicles to release insulin by exocytosis
Cause of type 1 diabetes
Beta cells of the islets are unable to produce insulin, could be caused by an autoimmune response where the cells of the immune system attack the beta cells
Cause of type 2 diabetes
Excess body weight, physical inactivity, habitual overeating of refined carbohydrates, cells can’t use insulin because the beta cells can’t produce enough insulin or the body cells don’t respond to insulin
Treatment of type 1 diabetes
Regular testing of blood glucose concentration using prick test (Sniggers), adjust insulin injections according to results, no prevention or cure
Treatment of type 2 diabetes
Diet, match carbohydrate intake to exercise, more exercise, drugs to stimulate insulin production or slow down glucose absorption from the small intestine
Issues of insulin obtained from animals
Expensive, extracted insulin is slightly different to human insulin so allergic reactions are possible
Alternatives to getting insulin from animals
Genetically modified bacteria, stem cells, pancreas transplants, beta cell transplants
Advantages of getting insulin from genetically modified bacteria
Purer form, fewer allergic reactions, more produced, cheaper, lack of religious or ethical issues
Disadvantages of pancreas transplants
Demand outweighs availability, immunosuppressant drugs
Disadvantage of beta cell transplants
Immunosuppressant drugs still required which increase the metabolic demand on insulin-producing cells
Advantages of stem cell treatments
No donor availability, reduced likelihood of rejection problems as embryonic stem cells are less likely to be rejected, no injections
Disadvantages of stem cell treatments
Ethical and religious issues, controlling growth and differentiation is hard so tumours might develop
